Ceramic filters are known in the art. Prior art ceramic bandpass filters are generally constructed from blocks of ceramic material, and have various geometric shapes which are typically coupled to external circuitry through discreet wires, cables, pins or surface mountable pads.
Some of the major objectives in electronic designs are to reduce physical size, increase reliability, improve manufacturability and reduce manufacturing costs.
Prior art duplex filters generally require various metallization schemes on a top surface to provide the desired frequency response. These duplex filters are difficult to reliably manufacture on a consistent basis, because if the top metallization scheme is varied slightly, the frequency response can be undesirably altered. Moreover, these devices are difficult or require additional process steps to suitably tune. For example, prior art tuning requires removing the bottom metallization, grinding a portion of the ceramic off the bottom, then remetallizing the bottom surface of the ceramic and baking the duplexer to release the unwanted solvents, and thereafter sintering the newly metallized bottom.
For these reasons, a duplex filter which overcomes many of the foregoing deficiencies would be considered an improvement in the art. It would also be considered an improvement, if a method and duplex structure could be simplified to make the tuning and manufacturing process easier and more reliable.